Some computing devices are configured to operate in multiple access modes, such as a reduced access mode (in which the computing device permits a user of the computing device to access a reduced set of functionality provided by the computing device) and a standard access mode (in which the computing device permits a user to access a relatively larger set of functionality provided by the computing device), and/or a full access mode (in which the computing device permits the user to access a complete set of functionality provided by the computing device). In some examples, a computing device may present one or more security challenges that a user is required to complete in order to change the operating access mode from a reduced access mode to a standard or full access mode. For example, a computing device may output, for display at a display device, a user interface screen including one or more user interface elements that prompt a user to input security information, such as a password, a personal identification number (PIN), a pattern or biometric data (e.g., fingerprint, voice, image, or the like). In response to receiving indications of the security information, the computing device and/or a remote computing device may compare the input security information to a saved copy of the security information, and, upon confirming a match, may change from the reduced access mode to the standard or full access mode.